Apparatus for centrifugal separation



Oct. 6, 1953 D. H. DAVIS 2,654,535

APPARATUS FOR CENTRIFUGAL SEPARATION Filed July 25, 1949 4 Sheets-Sheetl ll ml h H In. H

I I INVENTOR.

Fig-2 DEAN'H. DAVIS BY 5 I v JMMG/KWI/W ,ATTORNEYS Oct. 6, 1953 D. H.DAVIS APPARATUS FOR CENTRIFUGAL SEPARATION 4 Sheets-Sheet 2 Filed July25 1949 INVENTOR. DEAN H. DAVIS ATTORNEYS Ill/ 0. 1,1,11,11,11

Oct. 6, 1953 D. H. DAVIS APPARATUS FOR CENTRIFUGAL SEPARATION 4Sheets-Sheet 15 Filed July 25, 1949 R 8 m mD H. m E D M-qr VW ATTORNEYS.Oct. 6, 1953 D. H. DAVIS 2,654,535 APPARATUS FOR CENTRIFUGAL SEPARATIONFiled July 25, 1949 Sheets-Sheet 4 5 INVEA IMR. IQEAN .H. DAVISATTORNEYS Patented Oct. 6, 1953 APPARATUS FOR CENTRIFUGAL SEPARATIONDean H. Davis, Longmont, 0010. Application July 25, 1949, Serial No.106,613

1'7 Claims.

This invention relates to an apparatus for centrifugal separation ofheavier and lighter particles, more particularly of mineral particles orthe like, the heavier particles usually being valuable ore and thelighter particles usually being tailings or waste.

For the separation of heavier and lighter mineral particles, pulsatingjigs or reciprocating screens have often been used. In such jigs or thelike, pulp or a body of particles, normally consis ing of a mixture ofheavier and lighter particles is reciprocated at as fast a rate aspossible to produce separation, due to the inertia of the largerparticles and the consequent tendency for the lighter particles to movefurther at each pulsation or reciprocation. However, since not only thebody of particles being separated, but also the entire apparatus must bereciprocated, jigs and reciprocating screens have-normally consumed anundue amount of power. In addition, due to the limited rate ofreciprocation, the separation efiiciency has not been as high asdesired.

Among the objects of the present invention are to provide a novel methodof separating heavier and lighter particles, wherein centrifugal forceis utilized; to provide such a method in which separation can beeffectively accomplished and adequately controlled; to provide such amethod which may be carried out in more than one manner; to provideapparatus particularly adapted to carry out the method of thisinvention; to provide such apparatus which involves a minimum of movingparts, and therefore requires a minimum of power; to provide suchapparatus wherein the number of reciprocating parts is few, if any; toprovide such apparatus which may be made in a number of different forms;and to provide such apparatus which is relatively low in initial andinstallation costs and economical in both operation and upkeep.

The present invention utilizes centrifugal force as the primary forceproducing separation, but in the method of this invention, thecentrifugal force is periodically opposed by a rapidly pulsating forcewhich apparently retards or prevents the movement of lighter particleswith the centrifugal force to a greater extent than the heavierparticles. The heavier particles are thus moved away from the lighterparticles by centrifugal force, while the lighter particles aredischarged along a different path. Normally, a liquid such as water isemployed to carry the body of particles, both heavy and light, from oneplace to another, and in the method of this invention additional orauxiliary liquid is supplied, such additional water being normallysupplied to flow past the body of particles on the side in the directionin which the centrifugal force is acting and also is adapted to carryaway the heavier particles. A rapidly pulsating force may be produced byperiodically restricting or retarding the flow of auxiliary water, at apoint slightly beyond the body of particles in the direction of flow ofthe auxiliary water, so that the water tends to reverse its flow, backtoward the body of particles. Or, the pulsating force may be produced bythe condensation of a vapor, such as steam, successive portions ofwhich, when introduced into a body of water adjacent the body ofparticles and on the side of the direction in which centrifugal force isacting, will expand and then condense, Such intermittent expansion andcondensation of steam may be made to take place relatively rapidly,producing an effect similar to that commonly known as steam or waterhammer. Or, localized heating may be utilized to vaporize small portionsof the liquid or water, which upon vaporization expand and are thencondensed by the surrounding liquid or water, so that again a rapidlyintermittent or periodic force, opposing the centrifugal force, isproduced.

Apparatus particularly adapted to carry out the above method isillustrated in the accompanying drawings, in which:

Fig. 1 is a top plan view of a centrifugal separator constructed inaccordance with the present invention;

Fig. 2 is a side elevation of the same, shown partly in section takenalong ofiset line 22 of Fig. 1;

Fig. 8 is an enlarged horizontal section of a separating chamber orcompartment of the apparatus of Figs. 1 and 2, taken along offset line3-3 of Fig. 4;

Fig. 4 is a radial vertical section through the compartment, showingalso certain associated parts including a valve which is opened andclosed rapidly, the valve being in open position;

Fig. 5 is a View similar to Fig. 4, with the valve in closed position;

Fig. 6 is a further enlarged cross-section of the valve;

Fig. 7 is an arcuate vertical section, taken through the compartmentalong line l-'l of Fig. 4;

Fig, 8 is a vertical section of a compartment similar to that of Figs.3-7, but to which steam is supplied for producing a pulsating force;

Fig. 9 is a horizontal section taken through several adjacentcompartments or chambers of -preferably provided at the upper 3,000 B..P. .M. to produce .ing movements of valves 3 a slightly different formof apparatus constructed in accordance with this invention, to whichsteam is also supplied;

Fig. 19 is a top plan view, partly in horizontal section, of theapparatus which includes the comartments of Fig. 9; and

Fig. 11 is a side elevation, partly broken away and partly in section toshow the interior construction, of {the apparatus of Fig. 110.

As illustrated in Figs. 1 and 2, apparatus constructed in accordancewith this invention may include a plurality of compartments C, which aremounted for rotation on a mainsshait fisa'rriixture of heavier andlighter particles or pulp' being supplied to each compartment through .afeed pip-e it, which leads from a pulp feed launder H, each of whichrotatewithithe-num partrnent C. Pulp is supplied to launder l lirom astationary pipe I2, and the rotating assembly consisting of shaft Scompartments C and feed launder H is mounted centrally with resepect toa tank T, the upper end of which "is provided with a concentratedischarge launder 13 into which the heavier particles are dischargedfrom pipes l-. From concentrate launder 4'3, anoutlet pipe it conveysthe concentrates to a sump 1-5, from which the concentrates may be movedto the next point of 'ther grinding, flotation or shipment or movementdirectly to a-smlterorthe like. The tailrngsor lighter particlesare-discharged 'frpm each compartment in a manner explained later,through 'tailings 'outlet T4 and fall "into the tank T, the bottom =18of which may slope 'to pne side towardan outlet H3, as in'Fig. 2, fromwhich the tailingsmay be led to a settling p'en'd or' thelike.

For rotating the central assembly, *shafit "is provided at its lower'end with a pulley 2%, en gage'd 'by 'a belt 21, or shaft S 'may bedriven in any other suitable manner, such'a's 'by a direct *motor drive,while a suitable bearing 22 also Shaft Sis hollow to provide a passage211 for auxiliary-water from a supplypipeki led through the shaft to aseries *of 'distribut'ing pipes 26, -'one for each compartment C, asuitable riritatable sealing connection, preferably of a #converitionalnature and therefore not shown, being provided at the lower end of theshaft S, to ponnec't the pipe '25 and passage 23 in shaft 5. upper"shaft 27 is also hollow, for passage there'through of a pulsationcontrol shaft 28, provided at its end with a double grooved pulley 28,each groove being engaged by a -belt anthere preterably being two beltsextending in diametrically opposite directions, to balance the thrustirom the belts and thereby tend to maintain-the rotatin partsiii-alignment about the axis-of rotation. Each distributing pipe 25extends outwardly and then upwardly past the corresponding oompartment Cto -a pulsating device, such as a yaltve V, while the launder I I andc'ompartmrits C may be supported from the shafts in any suitable manner,such as partly by pipes 16 :and also by suitable structural elements,such -*as rings 53! and brackets 32. A suitable bear ing for auppershaft 21 may be provided, if desired. The shaft Send the compartments(3' along with it, are rotated at a suitable speed to produce thedesired centrifugal force, such as at about I50 RIP. while the pulsationcontrolshaft 28 is driven at a considerably higher speed, such as atabout rapid opening and picsas explainedbelow. Referring now to Figs.3-7, each comparttreatment, such 'as for fur-.

lower endo'f the share ment C may comprise an inlet chamber 35 and anoutlet chamber 35, separated by a screen 36, having a mesh of a suitablesize in accordance with the size of the particles being separated. Theinlet chamber 34 may be formed by a boxlike structure having an arcuaterear wall 31, top and bottom walls 38 and 39, respectively, side WallsGil and limited front walls GI and 42, along the latter or whichitaiilings outlet IT extends vertically, to permit adequate discharge ofthe .lighter particles. Screen 38 is mounttd in the space between thefront walls ii and 52, while .fiisposed, inwardly extending flanges 43and M are disposed at the opposite sides of thescreen. .The outletchamber 35 may be substantially pyramidal in shape, formed bytrir-arggnlazrttnpzandbottom walls and side walls .45, which converge toan outlet opening 51, to which distributing pipe 2-6 is connected, as bya nipple 48.

As in Fig. '3, the pulp from feed pipe 518, which enters theinletchani'ber 3'4 #at one s'iiie and za't an upper position, :as in 4,*tlue "to :pentriiugal force created "by rotation, bui'lds up along thefront wallet until it overfiows flange 153 and then forms an arcuate bed49 of material :or :mineral particles to be-separaltedmhichWlHiI'EStP'OXI-SCEBGD 36, "the thickness of the fbed 59 ibeingd'etermined -by-the2height of flanges 3 :and 31%. During operation, ofcourse, the -:bed :68 .of material Will The maintained .011 screen 35between the flanges. Centrifugal force will, ioi zcourse tend to throwthe material against the :outer "wall art the teampar'tment and the:screen 35 tending to maintain the b'ed from :top to bottom, against theLforce of -gravity. llh'e 'outlet chamber ttfiiwillnormal'ly :be filledwith Water, as L mm ith'e distributing :pipe 25, or primarily waterintroduced the pulp through feed "pipe xiii, the normal flow or" theauxiliary water, as 14., 'Ebeing upwardly .in distributing pipe-2t :pastnutlezt z'i.,tltrouglz1 valve V and thencethrongh pipe is into "thezconcen- "trate launder.

Thepulsatinns or periodieiornes opposing zcen- 'triiiugalfforcesarelprduced bydihe pulsaztm" galevice, in this instance :by rapid opening andclosing of "valve V, which upon iclo'stng, .as .in Big. -5, will"temporarily :restrict :normal flow of water and cause the water to tendto back up through the -.opening t! into the chamber 35. its indicatedpreviously, the pulsation control :shaift 23 is rotated at '13relatively high speed, such as 35000 B. P. rso fthatlthe ripening andclosing .01. the valvev will the ion the rorder :0f13,000 timesper:minute, less the :speedof :rota'tion 1'01 the shaft :5, which if .at.750 2P. ilvL'willtmean thatseachvalve X will open and .close about 2250times :per minute. Thus, there'willacitually beiinsuflicient time forwater to flow from the valve V back :to the opening 41, butrather-the'Water will .ioe in a-constant state of agitation,particularly on the discharge fSide fif screen .36, i. ethewater willtend to flow first one way and. then the :other. When the tendencytowardtflow isagainst screen .3 6,,1the water will push the lighterparticles back irom the screen,.since the lighter particles'iwillbee-carried more readily "by the :counterforce of the water than willthe heavier particle's. As .airesult, the .layeroi' material .next tothe screen will soon be -composed:dflheavierxparticles, which during thetendency of the water to flow away-from the screen 35, will'becarriedbycentr'rfugal force through the screen, and then be carried along withthe *water through the outlet and-thence through valve V and into "thedischarge launder.

The lighter particles will move along in the bed 59 toward the flangeat, over which they will flow to the tailings outlet I 1 whichpreferably extends from top to bottom of front wall 39, as indicatedpreviously, to facilitate the discharge of the lighter particles. Ofcourse, the concentration of heavier particles in the bed will decreasefrom the entrance flange 53 to the exit flange 44.

As in Figs. 4 and 5, the pulsation control shaft 28 may be provided atits lower end with a crank throw 58 and a crank pin 5 l, which isrotatable in a block 52 to which a series of rods 53, one for each valveV, are attached. Each valve V may be actuated. by a valve rod 54, whichreciprocates within a sleeve 55, which passes through a supporting andguide tube 56. As in Fig. 6, the sleeve 55 may also carry at its outerend a cone 57, adapted to engage an annular valve seat 58, formed at theoutlet of the valve V, cone 5'! preferably being made of or providedwith a layer of soft material, so that it can close effectively onmineral particles, which will normally be carried by the water flowingthrough the valve. Valve rod 54 preferably makes a lost motionconnection with the sleeve 55, as by locking nuts 59 mounted on theouter end of the valve rod 54, so that the valve will not openimmediately after closing, but there will be a slight period of restwhen the valve closes. Thus, as the valve rod moves outwardly, thepressure of water within the valve V will force th cone 5? against seat58, but the valve rod will travel sli htly further, such as to theposition of Figs. 5 and 6. Also, when the valve rod begins to moverearwardly, the valve will remain closed until the nuts 59 engage theend of sleeve 55. The valve will, of course, remain open and will notbegin to close until the crank. pin 5! reaches its extreme position,away from the particular valve V, such as shown in Fig. l. Preferably,the position of nuts 59 on valve rod 5 3 is adiusted so that the valvewill remain closed for about as long as it remains open. Of course, thistime will be relatively small, since if the valve o enings occur on theorder of 2250 times per minute, only a fraction of a second is consumedduring each o ening and clos ng. However, these rapid pulsationsintroduced into the auxiliary water, and which periodically produceforces opposing the centrifugal force within each compartment C, permitthe heavier par ticles to pass through the screen and tend to keep thelighter particles back from the screen, so that as the bed of materialmoves across the screen, more more of the heavier particles will passthrou h the screen, while the lighter particles will finally bedischarged over the flange l and into the tailings outlet ll, indicatedpreviously.

Any desired number of compartments C may be utilized. since the four comartments shown in Fig. 1 are illustrative only. Also, any other suitablemanner of actuating the valve V, and in fact any other suitable ty e ofvalve or means for intermittently or periodically restricting the flowof the auxiliary water, may be utilized. As indicated previously,instead of utilizing a valve or other means the pulsating device forperiodically restricting the flow of the auxiliary water, pulsatingdevice may introduce va or into the outlet chamber and the periodiccondensation of the vapor utilized to produce the desired pulsations.

A suitable modification adapted to carry out such vapor condensation isillustrated in Fig. 8, in which a steam supply tube 52 passes centrallydown an upper shaft 2'! to a steam distributing block 53, the upper endof tube 62 being provided with a suitable rotating seal, conventional innature and therefore not shown. A series of steam distributing pipes 64,one for each compartment, lead from the block 63 to each outlet chamber35' and comprises the pulsating devices. Steam may be introducedcontinuously into the water therein, since as steam enters from thedistributing pipe 64, it will expand to produce a force tending tooppose the centrifugal force produced by the rotation of the compartmentC, but will immediately be condensed, this expansion and condensationbeing repeated rapidly. The pressure and temperature of the steam ispreferably correlated with the conditions within the cham ber 35', sothat the expansions and condensations, with resultant pulsations, willtake place sufficiently rapidly to produceperiodic forces opposingcentrifugal force at a sufficiently rapid rate to cause effectiveseparation of the heavier and lighter particles.

The compartment C of Fig. 8 is similar to the compartment C of theprevious embodiment, except that the outlet chamber 35' is preferablymade slightly larger, to accommodatesteam introduction, as by thetriangular top and bottom walls and side walls d5 being longer. Also,the auxiliary water distributing pipes 26 are similar to the pipes 26 ofFig. 2, in extending outwardly and then upwardly past the outlets 4'! ofthe compartments, at which point each is connected with the outlet 41 bya nipple 48'. However, the upper end of each distributing pipe 26 doesnot lead to a valve, but rather merely terminates in a laundry dischargesection 65 which is preferably provided with a restricted outlet 66tending to restrict the flow of auxiliary water and insure that thechamber 35' will be full of water.

In the steam introduction embodiment of Figs. 9-4.1, the compartmentsmay have inlet chambers which are combined into a single annular inletchamber. Thus, a single casting may be made to produce a series ofoutlet chambers iii, similar to chambers 55 of compartments C in havingconverging, triangular top and bottom walls I! and side walls 12, ascreen 35' being individually mounted, as shown, between posts 73 whichseparate the chambers. If desired, a single screen, extending around theinner periphery of the casting, may be attached, as by spot welding orthe like, to each of the posts it? and also to the upper rim (4 andbottom 15 of the casting, as Will be evident from Fig. 11. As in Fig. 9,a pair of adjacent chambers iii are supplied with steam from a steamdistributing pipe it having a pair of branches ll, one of which connectswith each of the chambers.

As in Figs. 10 and 11, the flow of material alongthe screens at is frombottom to top, the feed thereto being beneath the outer edge of adistributing cone it, through the apex of which extends the mouth of astationary pulp feed pipe if, the pulp flowing beneath the cone ill andsubstantially equally to the lower portion of each screen 3%. Theheavier particles, as before, pass through the screen, while the lighterparticles are moved upwardly and over the rim 74, after which they arethrown by centrifugal force into the tank T to be discharged through thetailings outlet it. A steam and water distributor it may be madeintegral with the bottom 75 of the compartment casting, or may be madeseparately or by separate parts, such as plates and circumferentiallyapertured rings, and attached to the compartment coasting and to shafs2.

amass which as doeione, :is .hollow to provide a passage .24 z-ior watersupplied by auxiliary water supply mipe asibeforedheshaft S.-may beprovided .withfa pulleyldll driven by :a belt 22 l,,-and a bearing 1:2:inay also the provided. The steam and water distributor $.59maybeprovide'd with-a lower water .chembm $85, which connects with thewater ,passage {24' :in :shait SC, and with an upper .steam chamber :81,to which a centrally disposed steam :supply pipe 82.1leads from above,the latter being connected by a ;cenventional .rotary sealing connection.63 :with a stationary steam supply ;pipe 'Bil. :Steam pipe :82preferably extends through feed :pipe 1-2 and also centrally throughcone 'lddown to.-steam chamber .8 l.. Both-water chamber Bil andsteamchamber -81 are -provided with 'a number of outlets, .the :-number of@water outlets -:corresponding to the number .of charmhers, and the.numb.er of steam outlets, cor- .1

responding to one-half the :number -;of zchamhers, since each steamdistributing pipe 15 supplies "tfJIO chambers, as indicated previously.

water distributing pipe 185 may extend outnzardiyiand then upwardly to aT :86 connected :to the outlet 3 of the corresponding chamber 2128,while :a discharge pipe 8-7;, provided with -agoosetneck at the top fordischarge-of the aux- ;ili-ary water-and concentrates intotheconeentrate launder 13, extends upwardly from T 86.

During operation-of the apparatus of Figs. 9-11, the shaft S may berotated at a suitable speed, isuchzas 750 R. :P. M. as before, whilethe-pulp is "ted beneath cone 18 to the screens 3.6. .Centriiugal fiorce'will cause a bed of :mineral particles zto buildup'on the screen, whileeach :ch-amher it will be filled with water, including water thrownoutwardly through the screen from the incoming pulp, as well as waterfrom distributing pipe The --auxiliary water will flow continuously.into :the concentrate launder, :but-steamintroducedinto each chamber:10 will periodically i'expand, producing a force opposing centrifugalits ice, and then condense. As before, centrifugal force will move :theheavier particles through the screen, but *the lighter particles will beprevented from moving through the screen .by the'periodic steamexpansions. As indicated previously, the pulsations-or intermittentforces'produced by the steam are quite rapid in succession, so that theI water each chamber ill is in -a state of constant agitationn'.e.-tendencyto flow backthrou'gh the screen and. :then through theoutlet41. Also,

' the .bed behind :each screen -3.5-1wi1l build up:-un-

til it overflows the upper rim Jld, whereupon the tighter particlesviillbedischarged outwardlyjnto the tank T for ultimate dischargethrough tailings outlet Ii .Erom the foregoing, it will be apparent thatthe .method and apparatus. of this .inventionfulfil tea marked degreetherequirements and objects hereinhefore set forth. The production-ofarapidly pulsating .force, tending to oppose centrifugal ierce,particularly when produced in a liquid adjacent the point of separationbetween the heavierandlighter particles, tends-to insure that theseparation will not only .be ,efiective, .but also readily controlled.The utilization of anauxiliary stream of liquid, which tends to flow.past the point of separation and which carries with it the heavierparticles separated, simplifies the problem :of disposition of.suchheavier particles. The periodic obstruction of the normal flow :of

such should, -.preferabl-y at a :point closely adja- -oent shut beyondthe point of ;connection, :insures that pu sat ng io ces will betransmitted zrectlgy o the b d of par icle be n epara without lo sof-efiectiveness. (It can be seen that if rapid pulsations tareattempted .to be introduced into the .auxiliary stream of liquid priorto the outlet 41, such as in the supply pipe .25, the pulsations will.tend -.to merge and .loseeiiectiveness during flow through the pipes.In addition, =the pulsations cannot be made as .positive foy [attempting.to alternate the flow prior to the compartments, unless unduly .highpressures are .utihzed,.-since .the opening of -,a valve, to provide a.sudden rush or pulse of water, normally cannot be made as positive as.a stoppage of flow due to thesuddenolosing-of a iv-al-ve...In,thisiconneotion, it is to be vnoted that water hammer, :inhousehold pipes, invariably .takes .place .in the dine aheadsoi thenaive. or restriction producing it, and :not after.

.The alternative .method of .this invention, wherein a vapor, such .assteam, is periodica ly condensed @within .a hody of .liquid .disposed .ladially outwardly .from .the separating .bed of parti- .cles, both easyto apply .and economical to use. Also, .steam may besuppliedat aconstant pressure, since the .natural tendency for successive portions.of the .steam to expand .and condense within .such body .of liquid, istaken advantage of iii-a novel. and effective manner.

The apparatus adapted to carry out the above invention involves,primar'ily only rotating parts, which require a minimum of power, afterbeing brought up to speed. When valvesare utilized to .obstruct the how.ofauxiliary liquid, the reciprocating parts are few in number and lightin weight, so that little additional ,power .is required. When steam issupplied .to the outlet ,chanibers. ,there'are no reciprocatingpartsnecessary, so that additionally less motive power .is utilized..The absence of heavy reciprocating parts ,alsorreduces the initialcost-of .bearings,.driving parts and the like; reduces installation-.costs of heavy foundai-tions-and the like; and also reducesmaintenance :costs, as well .as eliminating vibration ,problems r in:adiacent or permeated equipment .or structures.

While'variousmaimers in which .the method of this invention may becarried out, and several forms and variations of the apparatus are.described, it will 'be understood that other changes maybe madetherein, and :that other fcrms and :manners 01 .carrying :out theunethod may exist, all -with01lt-.departing from the spirit and .scope:of rthlS invention.

at iselaimedfis Apparatus'iorseparatingheaviergand'lighterparticles-carried by liquid in ,-a pulp, which comzprises :a series of.circumferentially spaced .com- 'partments, each including .an outletchamber having :a radially outwardly spaced outlet an'd'a foraminouswall on the radially inward side of said chambers; means for rotatingsaid compart- 'ments about a central axis; means for supplying rpulptothe inner side ."of :each of said wforaminous wall; 'auxiliary watersupplymeans having ;a connection with each said routl'et "and adapted tosupply auxiliary liquid to flow past *said outlet andto apoint'ofdischarga'suchauxiliaryliquid "being adapted to 'carry 'with it heavierparticles passing through said foram'inous wall and then to said outlet;and means for introducing a :con- .densa-ble vapor into each saidchamber.

.52. Apparatusdfor separating heavier and lighter particlesoimineral-and the :like, which comprises -.a zoompartmentmotatable aboutan axissubstantially perpendicular thereto and having a screen extendingacross the same, a pulp inlet and a lighter particle outlet on the innerside of said screen, and a heavier particle outlet on the outer side ofsaid screen; means for rotating said compartment about said axis; meansfor supplying pulp to said pulp inlet; means connected with said heavierparticle outlet for supplying auxiliary water to said outlet, andconveying water and heavier particles from said outlet to a point ofdischarge; and a pulsating device located at a point between saidheavier particle outlet and said point of discharge for periodicallyimpeding the flow of water and heavier particles from said outlet.

3. Apparatus for separating heavier and lighter particles of mineral andthe like, as defined in claim 2, wherein said means for supplyingauxiliary water to said heavier particle outlet and conveying water fromsaid outlet comprises a pipe, and said pulsating device for periodicallyimpeding the flow of water and heavier particles from said outletcomprises a valve and means for opening and closing said valve rapidly.

4. Apparatus for separating heavier and lighter particles of mineral andthe like, as defined in claim 3, wherein said valve closes in thedirection of flow of water and heavier particles from said outlet.

5. Apparatus for separating heavier and lighter particles of mineral andthe like, which cornprises a compartment rotatable about an axissubstantially perpendicular thereto and having a screen extending acrossthe same, a pulp inlet and a lighter particle outlet on the inner sideof said screen, and a heavier particle outlet on the outer side of saidscreen; means for rotating said compartment about said axis; means forsupplying pulp to said pulp inlet; means connected with said heavierparticle outlet for supplying auxiliary water to said outlet, andconveying water and heavier particles from said outlet to a point ofdischarge, the flow of auxiliary water in said means being substantiallyuninterrupted up to said heavier particle outlet; and a pulsating devicelocated at a point in the path of flow of heavier particles between saidscreen and the point of discharge of said auxiliary water and heavierparticles, for producing periodic pulsations in the flow of waterthrough said compartment. which pulsations periodically oppose thecentrifugal force produced by rotation of said compartment.

6. Apparatus for separating heavier and lighter particles carried byliquid in a pulp, which comprises a series of circumferentially spacedcompartments, each including an outlet chamber having a radiallyoutwardly spaced outlet and a foraminous wall on the radially inwardside of said chamber; means for rotating said compartments about acentral axis; means for supplying pulp to the inner side of each saidforaminous wall; auxiliary water supply means having a connection witheach said outlet and adapted to supply auxiliary liquid to flow pastsaid outlet and to a point of discharge, such auxiliary liquid beingadapted to carry with it heavier particles passing through saidforaminous wall and then to said outlet; and means for periodicallyimpeding the flow of said auxiliary liquid and the particles carriedwith it at a point in the directon of fiow thereof beyond said outletconnection, to produce a pulsating force in said chamber periodicallyopposing the centrifugal force produced by rotation of saidcompartments.

7. Apparatus for separating heavier and lighter particles as defined inclaim 6, including a valve in each said supply means between saidchamber outlet and said point of discharge; and means for periodicallyopening and closing said valves.

8. Apparatus for separating heavier and lighter particles as defined inclaim 1, wherein such liquid comprises Water, and including means forintroducing steam into each said chamber.

9. In apparatus for separating heavier and lighter particles, acompartment having inlet and outlet chambers; said inlet chambers havingan arouate rear wall, end, top and bottom walls, and front walls oflimited extent providing an opening therebetween, a screen extendingacross said opening, an inwardly extending flange disposed vertically ateach side of said screen, a pulp inlet extending through said rear wallopposite the upper portion of one said front wall, and a tailings outletextending vertically along the opposite front wall; said outlet chamberhaving outwardly converging walls extending from said inlet chamber toan outlet opening for heavier particles; an auxiliary water supply pipeextending upwardly past and having a connection with said outletopening; means for supplying water to said auxiliary pipe at a pointbelow said connection; a valve in said pipe above said connection; meansfor rotating said compartment and pipe; and means for periodicallyopening and closing said valve.

10. Apparatus for separating heavier and lighter particles, whichcomprises a series of circumferentially spaced compartments, eachincluding an outlet chamber having a radially outwardly spaced outletand a foraminous wall on the radially inward side of said chamber; meansfor rotating said compartments about a central axis; means for supplyingpulp to the inner side of each said foraminous wall; a series ofauxiliary Water pipes, each having a connection with one of said outletsand adapted to supply a liquid to flow past said outlet and to a pointof discharge and to carry with it heavier particles passing through saidforaminous wall and to said outlet; valves in said pipes beyond saidconnections in the direction of flow of liquid in said auxiliary pipes;a cylindrical tank enclosing said compartments and adapted to receivelighter particles discharged from said compartments; a launder extendingaround the upper edge of said tank for receiving said dischargedauxiliary water; means for rotating said compartments; and means forperiodically opening and closing said valves.

11. Apparatus for separating heavier and lighter particles, Whichcomprises a series of circumferentially spaced chambers each havingwalls converging to an outwardly spaced outlet from a foraminous Wall onthe radially inward side of said chamber; means for rotating saidchambers about a central axis; means for supplyin pulp to the inner sideof each said foraminous wall; a series of auxiliary Water pipesconnecting to said outlets and adapted to supply a liquid to flow pastsaid outlets and to a point of discharge and to carry with it heavierparticles passing through said foraminous Wall and to said outlet; and aseries of steam distributing pipes, each extending to a point betweentwo adjacent chambers and having a branch leading to each such chamber.

12. Apparatus for separating heavier and lighter particles, comprising aseries of circum- 'aetgsss ferentially spaced compartments having inletand outlet chambers; said inlet chambers having an arcuate rear wall,end, top and bottom walls, and front walls of limited extent providingan opening therebetween, a screen extending across said opening, aninwardly extending flange disposed vertically at each side of saidscreen, a pulp inlet extending through said rear wall opposite the upperportion of one said front Wall, and a tailings outlet extendingvertically along the opposite front wall; said outlet chamber havinoutwardly converging walls extending from said screen to an outletopening; a lower shaft for supporting said compartments and having adriv ing attachment, said lower shaft having a water passage therein; anauxiliary water supply pipe connecting with said lower shaft passage; aseries of auxiliary water distributing pipes, each extending from saidshaft and upwardly past and having a connection with one of said outletopenings; an upper shaft providing a journal for a pulsation controlshaft; a double pulley on the upper end of said pulsation control shaft;a pair of diametrically opposed belts engaging said pulley in balancingrelation; a crank pin at the lower end of said pulsation shaft; a valvein each said auxiliary pipe at a point above said connection with saidoutlet opening, each said auxiliary pipe extending radially outwardlyfrom said valve; a valve rod for each valve connected with said crankpin, each said valve rod having a lostmotion connection with said valve;a generally cylindrical tank enclosing said compartments, said tankhaving a bottom sloping to a tailings outlet at one side for drainage oftailings received by said tank from said tailings outlets of saidcompartments; and a launder extending around the upper edge of said tankfor receiving water and concentrates discharged from said auxiliarypipes.

13. Apparatus for separating heavier and lighter particles, whichcomprises a generally cylindrical casting having a flat bottom, anoutwardly spaced, inwardly extending upper rim, and a series ofcircumferentially spaced outlet chambers each having a radiallyoutwardly spaced outlet, each said outlet having outwardly convergingwalls and said casting forming upright posts between said outletchambers, which posts extend from said casting bottom to said rim; ascreen extending between said posts across the opening to each saidoutlet chamber; a lower shaft for supporting said casting and having 'adriving attachment, said lower shaft having a water passage therein, "anauxiliary water supply pipe connecting with said lower shaft passage;means forming a water "distributor and a steam distributor at the upperend of said lower shaft, said water distributor connecting with saidlower shaft passage; "a series of-auxiliary water pipes extending fromsaid water distributor and upwardly to connect to said outlets, saidauxiliary pipes extending upwardly past said outlets and then outwardlyto'a point of restricted discharge; a pulp inlet pipe extending to acentral point over the bottom of said casting; an inverted cone throughthe apex of which said inlet pipe passes and having its lower edgespacedslightly above said casting bottom and adjacent said screens; a steaminlet pipe extending centrally through said pulp inlet pipe and cone andcasting bottom to said steam distributor; a series of steam distributingpipes extending from said steam distributor outwardly and then upwardlyto a point between alternate outlet chambers;

a branch steam pipe leading from each steam distributing pipe to the twoadjacent outlet chambers to connect with the interior thereof; acylindrical tank enclosing said casting and adapted to receive lighterparticles discharged over said rim; and a launder extending around theupper edge of said tank for receiving the discharge from said auxiliarypipes.

14. In apparatus for separating heavier and lighter particles, acompartment having inlet and outlet chambers; said inlet chambers havingan arcuate rear wall, end, top and bot-tom walls, and front walls oflimited extent providing an opening therebetween, a screen extendingacross said opening, an inwardly extending flange disposed vertically ateach side of said screen, a pulp inlet extending through said rear wallopposite the upper portion of one said front wall, and a "tailingsoutlet extending vertically along the opposite front wall; said outletchamber having outwardly converging walls extending from said inletchamber to an outlet opening; an auxiliary water supply pipe extendingupwardly past and connecting with said outlet opening; and a steam pipeextending into said outlet chamber.

15. In apparatus for separating heavier and lighter particles, acompartment having inlet and outlet chambers; said inlet chambers havingan arcuate rear wall, end, top and bottom "walls, and front walls oflimited extent providing an opening therebetween, a screen extendingacross said opening, an inwardly extending flange disposed vertically ateach side of said screen, a pulp inlet extending through said rear wallopposite the upper portion of one said front wall, and -a tailingsoutlet extending vertically along the opposite front wall; said outletchamber :having outwardly converging walls extending from said inletchamber to :an outlet opening; an auxiliary water supply pipe extendingupwardly past and connecting with said outlet opening; means forrotating said compartment .and pipe; and means for locally heating waterin said outlet chamber.

'16. Apparatus for separating heavier and lighter particles of mineraland the like, which comprises .a compartment having a fora'minous screenextending across the same; means for rotating said compartment tosubject material therein to centrifugal force; means for supplying apulp including a liquid carrying heavier and lighter particles to saidcompartment at a point inwardly of said screen; means for removinglighter particles from a point in said compartment inwardly of saidscreen, said compartment having an outlet for heavier particlesoutwardly of said screen; means for supplying a stream of auxiliaryliquid normally flowing past said conopartmerrt and communicating withsaid compartment at said heavier particle outlet; and a pulsating devicelocated in the pathof new of said auxiliary "liquid at a point in thedirection offlow thereof beyond said heavier particle outlet, forperiodically impeding the flow of such auxiliary liquid to produce apulsating force which opposes such centrifugal force periodically.

1W. Apparatus for separating heavier and lighter particles of mineraland the like, which comprises a compartment having a fora-ruinous screenextending across the same; means for rotating said compartment tosubject material therein to centrifugal force; means for supplying apulp including a liquid carrying heavier and lighter particles to saidcompartment at a point inwardly of said screen; means for removing.

lighter particles from a point in said compart- References Cited in thefile of this patent mer t inwardly of said screen, said compartmentUNITED STATES PATENTS having an outlet for heavier particles outwardly Dt of said screen; means for supplying a stream of Number ,Name aauxiliary liquid normally flowing past said com- 5 935,311 Lalst Sept909 partment and communicating with said compart- 1304132 Prentlss July1914 ment at said heavier particle outlet; and means i'gggggg 523 5 gfi133g for introducin team into sai com artment at 1 g s d p 1,512,469Kellogg Oct. 21, 1924 a point outwardly of said screen, to produce apulsating force opposing such centrifugal force 10 by periodic steamcondensation.

DEAN H. DAVIS.

